Need 2 separate elements of add_shortcode for presentation

You might want to declare arguments for shortcodes. Here is documentation, and things you need to improve in your code to make it work.

Change

function show_game_category_images_func()

to

function show_game_category_images_func($atts)

Add following code at the top of your function:

$a = shortcode_atts( array(
    'id' => '1',
), $atts );

Now inside $a['id'] is value passed as argument when declaring shortcode, for example [show_game_category_images id=2]